A telecommunication system may be arranged to provide a fixed line connection for a calling subscriber. According to another possibility the communication is based on a wireless, such as a radio frequency connection between the subscriber and at least one network element of the telecommunications system. An example of the first mentioned is the public switched telephone network (PSTN), and an example of a wireless radio communication network is the public land mobile network (PLMN). In addition, a communication may be established over one or more data networks. An example of this is the voice over IP (Internet Protocol) arrangement enabling voice call over a packet switched data network. The system may also employ a combination of wireless, fixed line and data communication for a connection. In the following the term “connection” is to be understood to mean all types of communication connections from and/or to a user terminal, such as a voice or multimedia call or a data communication session.
Telecommunication networks typically operate in accordance with a given standard which sets out what the elements of the network are permitted to do and how that should be achieved. In addition to basic voice and data services, the users of the subscriber terminals (such as fixed line telephones, data processing devices or PLMN mobile stations), would like to have other services available. Examples of these additional services include voice mail, the forwarding of a call to a different telephone (e.g. when the mobile station is switched off or the terminal is involved in a different call), prepaid charging, various alerts provided to the user via his/her terminal, caller identity presentation, number to name translations and vice versa, virtual private numbering and so on. The additional services requested and subsequently invoked for a connection may require control of at least one of the functionalities of the connection (routing, charging, duration, provision of connection or user related data and so on). A service providing a control functionality affecting a connection will be referred to in the following as a controlling service. The controlling service is a service provided with an authority to issue control instructions (such as modification of connection instance data, connection manipulation, charging or routing or duration control) for the same connection.
A modern telecommunication system may be provided with the so called intelligent network (IN) concept. The term “intelligent network” was introduced by the BELLCORE organisation (USA) in the mid eighties. The IN concept was developed in order to increase the flexibility and competitiveness of the telecommunication network architecture. Even though the initial IN architectures were developed to implement only certain specific services, for example service number, the current IN solutions provide the telecommunication network operators with a possibility to implement new, powerful services in their networks in a fast and cost-effective manner. The basic principles and operation of the IN applications are well known, and therefore they are not described herein in more detail. It is sufficient to note that in general the IN architecture comprises a (service) switching point (SSP) for triggering a call to the IN services and a (service) control point (SCP) for providing the service. A more detailed description of the general IN concept can be found e.g. from the recommendations by the International Telecommunications Union (ITU-T), such as IN Capability Set CS-1 published in 1993. The IN concept can be implemented in the fixed land line networks, such as the public switched telephone network (PSTN), or the wireless radio communication networks, such as the public land mobile network (PLMN).
For example, in the currently proposed intelligent network (TN) architecture for mobile telecommunication systems, an enquiry for instructions is issued from a mobile services switching centre (MSC) to an external service control point (SCP; the service provider). The signalling between the MSC and the SCP is commonly based on the Signalling System No. 7 (SS7) protocol suite. The interface between the mobile services switching centre and the service control point may be in the intelligent network application protocol (INAP) or the customised applications for mobile network enhanced logic (CAMEL) application part (CAP) protocol. Where an open CORBA (common object request broker architecture) interface is provided, the CORBA interface will hide the INAP or CAP protocol from the external service providers. Instead higher level service features are provided to the external service providers. This open interface is defined to the customised application for mobile network enhanced logic (CAMEL) service environments (CSE), subscriber identity module (SIM) application toolkit (SAT) servers or mobile station execution environments (MEXE) servers. The CAMEL service environment (CES) provides the execution environment within a CAMEL SCP executing a service logic. The proposal has the problem that the signalling between the mobile services switching centre and the CAMEL service environment uses the SS7 standard which is not considered as particularly flexible.
The services that may be used for the call or session can be external i.e. independent services from the telecommunication network used for the communication. The allowable additional services are specified in the associated standards. This means that a network operator may not be able to offer a new service if it is not specified in the standard. The time taken for a new service to be accepted into a standard may be relatively long.
An open service architecture has therefore been proposed in which the service capabilities will be standardised but not the services themselves. The open service architecture allows for externally provided services and effectively provides a translation service which allows the network and the external service providers to interact. The service capabilities will consist of bearers (connections) defined by quality of service parameters as well as the mechanisms needed to provide the services. It has been suggested that open interfaces based on distributed object techniques be used. An example of such open interfaces are those based on the CORBA (common object request broker architecture) standard referred to above. The network protocols are hidden from the service designers. This permits service providers including value added service providers to use the open interfaces for the service design.
The current telecommunications networks may employ a sequence of switches for controlling the routing of a call. Each of the switches may invoke their own controlling service for the call connection. This is a drawback when considering the overall management of the control functions provided by the several services for a communication.
In WO97/07637 a communication system for call handling is described employing a single switch for triggering the call to multiple services. In response to a trigger being detected in a call, service arbitration logic provides a particular service to a subscriber by routing the subscriber to the location in which the logic for performing the service is located. This location may be in a third party service provider. In one of the embodiments shown in this document, three service providers are provided with the middle service provider being connected to the other two. If more than one service responsive to a common trigger point is required, the trigger information is passed to a first third party service provider which passes this information on to the other third party service providers which provide a service in response to the same trigger. Thus the arrangement shown in this document suggest provision of services to a subscriber unit by numerous SCPs. The service arbitration logic is located at a “primary” SCP that passes information relating to a trigger to a “secondary” SCP. However, the information may pass via several such service providers which do not necessarily provide the subscriber with a service in response to the detected trigger, thereby increasing the amount of signalling in the system. In addition, the is no suggestion in the document how to actually detect services and/or proceed with services that provide call control features for a call.
Thus, a problematic situation may occur when more than one independently designed controlling service is requested for a call from a common trigger point, as the controlling features may be in conflict with each other and/or may interact and may thus not be used for a single call. In the prior art proposals the services may be invoked in such an order that only some of the controlling services to which the user has subscribed are in practice available to the user or can be successfully invoked. Multiple controlling services may have a disadvantageous influence to other services, or may even cause a malfunction to the telecommunications system or block the system if used at the same time for a call.